1. Field of the Invention
The present invention relates to a method for manufacturing hollow fiber piles, in which the hollow fibers are arranged in planes lying parallel to one another, the hollow fibers of each plane being arranged substantially parallel and at least partially spaced apart from one another, the hollow fibers of adjacent planes crossing one another and adjacent end regions of the hollow fibers being connected with one another at least spotwise.
2. Description of the Related Art
A device for filtering gaseous or fluid dispersions through the porous walls of hollow fibers is known from DE-OS 38 23 858, in which the porous hollow fibers are arranged in a plurality of superimposed hollow fiber layers with the open ends of the hollow fibers being embedded in a tubular embedding material. The latter encloses a flow duct for containing the dispersion to be filtered and which is non-permeable to the dispersion. The hollow fiber arrangement of this known device can be obtained by stacking a number of individual filter elements on top of one another. Each individual filter element is formed by being punched out of a conventional flat hollow fiber article, such as, for example, a hollow fiber mat, hollow fiber cloth or the like. After a number of individual filter elements are stacked one on top of the other, the hollow fiber stack obtained in this manner is subjected to an embedding procedure, in which the hollow fiber ends are embedded in the tubular embedding material. In the resulting structure, the porous hollow fibers within one layer of the hollow fiber stack can be advantageously arranged parallel to one another. Additionally, the hollow fibers of adjacent layers can preferably cross one another. The punching out of the filter elements can also be effected along with a simultaneous welding of the cutting sites.
In this known method, it is first necessary to manufacture a flat hollow fiber article, wherein the hollow fibers are arranged in a substantially solid formation, so that the flat article can be safely handled, i.e., for example, rolled together, transported, rolled up, spread out, stacked, etc., without the arrangement of hollow fibers, i.e. the parallel position for example, being lost in the flat article. The resulting manufacturing process for the filter elements is therefore complicated and also entails the danger of the hollow fibers already being damaged during the manufacture of the flat hollow fiber article and/or during the subsequent handling thereof. Flat hollow fiber articles of this type often also comprise means for securing the hollow fibers, such as warp threads, which necessarily remain in the hollow fiber stacks and therefore also in the filter device, which is not always desirable or advantageous.
A method for manufacturing a hollow fiber bundle is known from EP-Bl-0 093 677, in which at least one hollow fiber from at least one bobbin is wound by means of a thread guide device onto alternate outer ends of a drum, the hollow fibers forming successive layers and overlapping one another from one layer to the next. The hollow fibers are cut along longitudinal planes, which are parallel to the axis of the drum, at regular intervals essentially corresponding to the length of the desired bundles, so that a plurality of hollow fiber mats of overlapping fibers are formed, which are substantially flat and are open at both outer ends. Each of the hollow fiber mats formed in this manner is rolled up spirally in the longitudinal direction in order to form a corresponding number of hollow fiber bundles.
The manufacture of hollow fiber piles is not taught or suggested by EP-Bl-0 093 677. Additionally, as a result of the rolling up of the hollow fiber mats, the initially formed uniform arrangement of the hollow fibers is partially destroyed because the means provided for at least temporarily securing the cut ends of the hollow fibers to the substrates, cannot prevent a displacement and shifting of the hollow fibers.